Network Working Group B. Leiba
Internet-Draft Huawei Technologies
Updates: 2119 (if approved) August 09, 2016
Intended status: Best Current Practice
Expires: February 08, 2017
Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words
draft-leiba-rfc2119-update-00
Abstract
RFC 2119 specifies common key words that may be used in protocol
specifications. This document aims to reduce the ambiguity by
clarifying that only UPPERCASE usage of the key words have the
defined special meanings, and by deprecating some versions of the key
words.
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1. IntroductionLeiba Expires February 08, 2017 [Page 1]Internet-Draft RFC 2119 Clarification August 2016
RFC 2119 specifies common key words, such as "MUST", "SHOULD", and
"MAY", that may be used in protocol specifications. It says that
those key words "are often capitalized," and that has caused
confusion about how to interpret non-capitalized words such as "must"
and "should".
This document updates RFC 2119 by clarifying that only UPPERCASE
usage of the key words have the defined special meanings. It also
reduces wording conflicts by deprecating some synonymous key words.
This document will become part of BCP 14 when it is approved. [[RFC-
Editor: Please change the previous sentence to "This document is part
of BCP 14."]]
1.1. Some Notes for Reviewers (not for publication)
[[RFC-Editor: Please remove this section before publishing.]]
This update is intentionally small and focused, and quite
intentionally updates, but does not replace, RFC 2119. The author
considers it important to retain the reference to RFC 2119 because of
the general familiarity with the number, and to phase in the use of
"BCP 14". Note, though, that the References section uses the RFC
numbers, not the BCP number. This is because is needs to be clear
when a document has adopted this update, and the dual reference to
RFC 2119 *and* this document gives that clarity.
The point has been made by some that having case be significant to
the meanings of words is unusual and may be a bad idea. There is
specific concern about causing confusion to readers whose native
languages do not have a distinction between upper and lower case
(consider Chinese and Hebrew, for example). The author believes this
has been discussed and addressed, and that those maintaining this
point are in the rough. That said, it may still be worth continuing
the discussion a bit.
There have been suggestions that while we're here we should consider
a broader BCP 14 update that also talks about proper use of the key
words, when they should not be used, avoiding overuse, and so on.
The author agrees, but thinks is best to keep that as a separate
effort, as coming to consensus on such an update is likely to be much
more difficult, and is likely to take much longer.
2. Clarifying Capitalization of Key Words
The following change is made to [RFC2119]:
=== OLD ===
In many standards track documents several words are used to signify
the requirements in the specification. These words are often
capitalized. This document defines these words as they should be
interpreted in IETF documents. Authors who follow these guidelines